Commit f0d4f30a authored by Ingo Molnar's avatar Ingo Molnar
Browse files

x86/fpu: Split copy_xstate_to_user() into copy_xstate_to_kernel() & copy_xstate_to_user() 

copy_xstate_to_user() is a weird API - in part due to a bad API inherited
from the regset APIs.

But don't propagate that bad API choice into the FPU code - so as a first
step split the API into kernel and user buffer handling routines.

(Also split the xstate_copyout() internal helper.)

The split API is a dumb duplication that should be obviously correct, the
real splitting will be done in the next patch.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/20170923130016.21448-3-mingo@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 656f0831

arch/x86/include/asm/fpu/xstate.h

+2 −2
Original line number Diff line number Diff line
@@ -48,8 +48,8 @@ void fpu__xstate_clear_all_cpu_caps(void); 
void *get_xsave_addr(struct xregs_state *xsave, int xstate);

const void *get_xsave_field_ptr(int xstate_field);

int using_compacted_format(void);

int copy_xstate_to_user(unsigned int pos, unsigned int count, void *kbuf,

			void __user *ubuf, struct xregs_state *xsave);

int copy_xstate_to_kernel(unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf, struct xregs_state *xsave);

int copy_xstate_to_user(unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf, struct xregs_state *xsave);

int copy_user_to_xstate(const void *kbuf, const void __user *ubuf,

		     struct xregs_state *xsave);

#endif

arch/x86/kernel/fpu/regset.c

+4 −1
Original line number Diff line number Diff line
@@ -92,6 +92,9 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset, 
	fpu__activate_fpstate_read(fpu);



	if (using_compacted_format()) {

		if (kbuf)

			ret = copy_xstate_to_kernel(pos, count, kbuf, ubuf, xsave);

		else

			ret = copy_xstate_to_user(pos, count, kbuf, ubuf, xsave);

	} else {

		fpstate_sanitize_xstate(fpu);

arch/x86/kernel/fpu/xstate.c

+103 −7
Original line number Diff line number Diff line
@@ -924,7 +924,103 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, 
 * This is similar to user_regset_copyout(), but will not add offset to

 * the source data pointer or increment pos, count, kbuf, and ubuf.

 */

static inline int xstate_copyout(unsigned int pos, unsigned int count,

static inline int

__copy_xstate_to_kernel(unsigned int pos, unsigned int count,

			void *kbuf, void __user *ubuf,

			const void *data, const int start_pos,

			const int end_pos)

{

	if ((count == 0) || (pos < start_pos))

		return 0;



	if (end_pos < 0 || pos < end_pos) {

		unsigned int copy = (end_pos < 0 ? count : min(count, end_pos - pos));



		if (kbuf) {

			memcpy(kbuf + pos, data, copy);

		} else {

			if (__copy_to_user(ubuf + pos, data, copy))

				return -EFAULT;

		}

	}

	return 0;

}



/*

 * Convert from kernel XSAVES compacted format to standard format and copy

 * to a kernel-space ptrace buffer.

 *

 * It supports partial copy but pos always starts from zero. This is called

 * from xstateregs_get() and there we check the CPU has XSAVES.

 */

int copy_xstate_to_kernel(unsigned int pos, unsigned int count, void *kbuf,

			void __user *ubuf, struct xregs_state *xsave)

{

	unsigned int offset, size;

	int ret, i;

	struct xstate_header header;



	/*

	 * Currently copy_regset_to_user() starts from pos 0:

	 */

	if (unlikely(pos != 0))

		return -EFAULT;



	/*

	 * The destination is a ptrace buffer; we put in only user xstates:

	 */

	memset(&header, 0, sizeof(header));

	header.xfeatures = xsave->header.xfeatures;

	header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR;



	/*

	 * Copy xregs_state->header:

	 */

	offset = offsetof(struct xregs_state, header);

	size = sizeof(header);



	ret = __copy_xstate_to_kernel(offset, size, kbuf, ubuf, &header, 0, count);



	if (ret)

		return ret;



	for (i = 0; i < XFEATURE_MAX; i++) {

		/*

		 * Copy only in-use xstates:

		 */

		if ((header.xfeatures >> i) & 1) {

			void *src = __raw_xsave_addr(xsave, 1 << i);



			offset = xstate_offsets[i];

			size = xstate_sizes[i];



			ret = __copy_xstate_to_kernel(offset, size, kbuf, ubuf, src, 0, count);



			if (ret)

				return ret;



			if (offset + size >= count)

				break;

		}



	}



	/*

	 * Fill xsave->i387.sw_reserved value for ptrace frame:

	 */

	offset = offsetof(struct fxregs_state, sw_reserved);

	size = sizeof(xstate_fx_sw_bytes);



	ret = __copy_xstate_to_kernel(offset, size, kbuf, ubuf, xstate_fx_sw_bytes, 0, count);



	if (ret)

		return ret;



	return 0;

}



static inline int

__copy_xstate_to_user(unsigned int pos, unsigned int count,

		      void *kbuf, void __user *ubuf,

		      const void *data, const int start_pos,

		      const int end_pos)
@@ -977,7 +1073,7 @@ int copy_xstate_to_user(unsigned int pos, unsigned int count, void *kbuf, 
	offset = offsetof(struct xregs_state, header);

	size = sizeof(header);



	ret = xstate_copyout(offset, size, kbuf, ubuf, &header, 0, count);

	ret = __copy_xstate_to_user(offset, size, kbuf, ubuf, &header, 0, count);



	if (ret)

		return ret;
@@ -992,7 +1088,7 @@ int copy_xstate_to_user(unsigned int pos, unsigned int count, void *kbuf, 
			offset = xstate_offsets[i];

			size = xstate_sizes[i];



			ret = xstate_copyout(offset, size, kbuf, ubuf, src, 0, count);

			ret = __copy_xstate_to_user(offset, size, kbuf, ubuf, src, 0, count);



			if (ret)

				return ret;
@@ -1009,7 +1105,7 @@ int copy_xstate_to_user(unsigned int pos, unsigned int count, void *kbuf, 
	offset = offsetof(struct fxregs_state, sw_reserved);

	size = sizeof(xstate_fx_sw_bytes);



	ret = xstate_copyout(offset, size, kbuf, ubuf, xstate_fx_sw_bytes, 0, count);

	ret = __copy_xstate_to_user(offset, size, kbuf, ubuf, xstate_fx_sw_bytes, 0, count);



	if (ret)

		return ret;

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